Apparatus for breaking off side margin of wire glass plate

ABSTRACT

The apparatus is essentially constituted of: a glass-grasping mechanism connected to an end of a first rod normally arranged parallel to the glass plate on which a cut line is scored; a rod linkage comprised of five pivotally linked rods including the first rod, two of them parallel to the first rod and extending in the direction of the afore-mentioned end and the other two perpendicular to the first rod; two shafts arranged perpendicular to all the rods and respectively connected to the ends of the two rods parallel to the first rod; a first actuator for turning one of the shafts such that the connected rod and hence the first rod once rotate clockwise around the shaft and then anticlockwise to exert bending forces on the glass side margin; and a second actuator for holding the glass-grasping mechanism normally such that the side margin is kept parallel to the first rod and rotating the mechanism relatively to the first shaft in a plane perpendicular to the glass plate at the end of the anticlockwise rotation of the rods thereby to exert a pulling force on the wires left unbroken across the cut line.

[ Sept. 23, 1975 Primary Examiner-J. M. Meister Assistant Examiner-Fred A. Silverberg [57] ABSTRACT The apparatus is essentially constituted of: a glass grasping mechanism connected to an end of a first rod normally arranged parallel to the glass plate on which a cut line is scored; a rod linkage comprised of five pivotally linked rods including the first rod, two of them parallel to the first rod and extending in the direction of the afore-mentioned end and the other two perpendicular to the first rod; two shafts arranged perpendicular to all the rods and respectively connected to the ends of the two rods parallel to the first rod; a first actuator for turning one of the shafts such that the connected rod and hence the first rod once rotate clockwise around the shaft and then anticlockwise to exert bending forces on the glass side margin; and a second actuator for holding the glass-grasping mechanism normally such that the side margin is kept parallel to the first rod and rotating the mechanism relatively to the firstshaft in a plane perpendicular to the 1 glass plate at the end of the anticlockwise rotation of the rods thereby to exert a pulling force on the wires left unbroken across the cut line.

8 Claims, 10 Drawing Figures Data Offenbacher..............:::.

FOREIGN PATENTS OR APPLICATIONS 20,167 Germany APPARATUS FOR BREAKING OFF SIDE MARGIN ()F WIRE GLASS PLATE lnventor: Toshihiro Suzuki, Kurume, Japan Assignec: Central Glass Company, Limited,

Ube, Japan Filed: Nov. 22,

Appl. No.: 526,461

Foreign Application Priority Nov. 27, 1973 US. Cl. Field of Search References Cited UNITED STATES PATENTS 7/1965 Aksnes et al.

United States Patent Suzuki S mm Sm. 23,1975 Sheet 1 0M- 3,97,185

US atent Sept. 23,1975 shw 2 of4 13,97,185

US Patent Sept. 23,1975 Sheet 3 of4 3,907,185

US Patent Sept. 23,1975 Sheet4 of4 3,907,185

APPARATUS FOR BREAKING OFF SIDE MARGIN OF WIRE GLASS PLATE This invention relates to apparatus for breaking off a part of a plate glass and more particularly to apparatus for breaking off a side margin of a' wire glass plate.

In the manufacture of wire-reinforced plate glass, it is usually necessary to break off the side margins of the glass plate. The side margin is usually broken off by the following manual procedures. Preliminarily a cut line is scored on the glass plate and then the margin of the glass sheet is held along the cut line with a suitable grasping tool such as tongs. A downward force, if the glass plate is held horizontally, is exerted on the tongs to snap off the margin along the cut line. Although the glass is easily snapped or cut into two pieces by this action, the wires of the wire net embedded in the glass are left unbroken. The marginal portion, therefore, is repeatedly bended upwards and downwards, until the wires are completely broken due to work hardening thereof in the bended regions and tensile forces accompanying the bending.

The result of this method is generally satisfactory from the viewpoint of neatness of the broken edge, but the method requires many hands and hence causes the production cost to increase. Besides, such manual handling of glass occasionally causes injuries of the workers.

It' is therefore an object of the present invention to provide apparatus for automatically break off the side margin of a wire glass plate along a out line scored thereon, which apparatus can remove the margin reliably and give as neat a broken edge as one obtained by a conventional manual work.

Apparatus according to the invention is generally constituted of: first means to grasp the side margin of the wire glass plate placed in a predetermined position, which means is mounted on a support member; a rod linkage of five rods including one connected with the support member; second means to turn a shaft to which another of the rods is fixed perpendicularly; and third means to keep the support member normally in a position and cause rotational movement thereof relatively to the rod connected thereto at a predetermined stage of the operation. In the rod linkage, a first rod is arranged parallel to the wire glass plate in the predetermined position, and the support member is pivotally joined with an end of this rod in such a manner that the support member is rotatable in a plane perpendicular to the glass plate. A second and a third rods are arranged parallel to each other and perpendicular to the first rod and pivotally linked with the first rod respectively at a first and a second distances,'the latter being longer, from the afore-mentioned end of the rod. A fourth rod is parallel to and spaced from the first rod and pivotally linked with both the second and third rods. The fourth rod is fixed to a first shaft having a fixed axis perpendicular to both the first and second rods at a third distance from the second rod in the direction of the support member. A fifth rod is arranged parallel to and spaced from the fourth rod and fixed to a second shaft having a fixed axis parallel to the first shaft at the same distance from the second rod and in the same direction astthe fourth rod. The second means turns one of the first andsecond='shafts on the'axis thereof in sucha manner'that the'shaft is subjected to at least one cycle of turns consisting of a first turn through a first angle, a second turn in the reverse direction through a second angle larger than the first and a third turn into the initial position, so that the fourth, fifth and first rods are rotated all in the same directions through movements of the second and third rods along the respective axes thereof. The third means holds the support member normally in a position such that the side margin of the glass plate is kept parallel to the first rod and rotates the support member around an axle for joining the first rod therewith when the second turn of the shaft is completed, so that a pulling force is exerted on the wires of the glass plate lying across the cut line.

Apparatus of the invention has principal advantages that the apparatus can break off the glass plate margin together with the wires to give a quite neat broken edge since the operation of the apparatus is constituted of a series of steps essentially similar to those in a manual work and that the entire operation is carried out automatically and continuously by a comparatively small motive power,

The invention will be fully understood from the following detailed description of the preferred embodiments thereof with reference to the accompanying drawings, in which:

FIG. 1 is a perspective view of apparatus for breaking off a margin of a wire glass plate in accordance with the invention; I

FIG. 2 is a front elevation of the apparatus of FIG. 1;

1 FIG. 3 is an enlarged view of the front elevation of the glass-graspingmechanism of the same apparatus;

FIG. 4 is a series of diagrams showing the essential rod-linkage of the same apparatus as well as the function thereof; 1

FIG. 5 is a series of schematic front views of a wire glass plate showing the behavior of its sidemargin during one cycle of the operation of the apparatus of FIGS. l-3; and

FIGS. 6-10'are diagrams each showing one modification of the rod-linkage of FIG. 4.

As seen in FIG. I, a preferred embodiment of apparatus according to the invention is generally constituted of two identical linked rods blocks A, each of which is provided with a grasping mechanism B, and a driving mechanism block C. The two linked rods blocks A are associated with the-driving mechanism block C by a primary shaft 10, which is rotatably mounted on a frame 12 by means of a plurality of bearing stands 14. In each linked rods block A, a second shaft 16 is rotatably supported by two bearing stands 18, which are fixed to the f jame. 12. The second shaft 16 is arranged above and parallel to the primary shaft 10. A pair of straight and parallel first rods 20 are fixed to the primary shaft 10 and extend therefrom perpendicularly thereto and horizontally. A pair of straight and parallel second rods 22 are fixed to the second shaft 16 in such a manner that they extend in the same direction as and parallel to the first rods 20. The first rods 20 are pivotally linked with a vertical third rod 24 at a distance from the extended ends thereof by means of a first free axle 26 and similarly linked with a vertical fourth rod 28 at the extended ends thereof by means of a second free axle 30. Thesecond shafts 16 are also pivotally linked with the third rod 24 by means of a third free axle 32. Both the third and fourth rods 24 and 28 extend downwards from first rods 20 and pivotally linked with a pair of horizontal and parallel fifth rods 34 by means of a fourth free axle 36 and a fifth free axle 38,

respectively. All the above free axles 26, 30, 32, 36 and 38 are parallel to the first shaft 10. The fifth rods 34 extend parallel to the first rods 20 from the fourth axle 36 towards the first shaft 10. Thus a quadri-joint parallelogram is formed by the two horizontal rods 20 and 34 and two vertical rods 24 and 28 as seen more easily in FIG. 2.

A pair of parallel support plates 42 of a the glassgrasping mechanism B are rotatably joined with the extended ends of the fifth rods 34 by .means of a sixth axle 40, which is also parallel to the first shaft 10. Thesupport plates 42 are normally kept in a predetermined position relatively to the fifth rods 34 and rotated on the axle 40 at a predetermined stage of the operation of the apparatus by the following mechanism. Referring to FIG. 2,.a bracket 44 is fixed to the fifth rod 34 and supports thereon a first actuator such as a pneumatic actuator 46 having a plunger 48 by means of a seventh axle 50. The actuator 46 is arranged in such a manner that the plunger 48 is normally parallel to the fifth rod 34, and the extended end of the plunger 48 is pivotally joined with the support plates 42 by means of a pin 52. The pin 52 is parallel to the seventh axle 50 and located near the lower ends of the plates 42 and relatively remote from the sixth axle 40.

A second actuator 54, e.g. of the pneumatic type, is mounted on one of the support plates 42 to lie therebetween in such an arrangement that a plunger 56 thereof extends horizontally and in the opposite direction to the fourth axle 36. The extended end of the plunger 56 is pivotally joined with two connecting rods 58, one extending vertically and upwards and the other also vertically but downwards, by means of a pin 60. The pin 60 is arranged parallel to the fourth rod 36 and allows the connecting rods 58 to rotate thereon. A pair of glassgrasping plates 62 are respectively connected to the upper and lower connecting rods 58 in the following manner. Referring to FIG. 3, each glass-grasping plate 62 is fixed to a first side of an angled support plate 64, of which vertical cross section is generally L-shaped. The other side of the support plate 64 is joined with one of the connecting rods 58 by means of a horizontal pin 66, which is isolated from the support plates 42 and allows the connecting rod 58 to rotate thereon. The first side of the support plate 64 is rotatably joined with the support plates 42 by means of a horizontal pin 68. Both the pins 66 and 68 are parallel to the fourth axle 40. The glass-grasping plates 62 are arranged so as to grasp or hold a side margin 70a of a wire glass plate 70, which lies horizontally on conveyer rolls 72, from the upside and downside when the plunger 56 protrudes from the second actuator 54 to cause the connecting rods 58 and the support plates 64 to rotate.

Referring again to FIGS. 1 and 2, the driving mechanism C of the apparatus is constructed as follows. The primary shaft is provided with two brackets 74 and 76 at the middle section thereof. The two brackets 74 and 76 are rotatable on the primary shaft 10 and support a first push board 78 and a second push board 80, respectively, both of which are arranged parallel to the primary shaft 10 and opposite to each other. A third actuator 82, e.g. of the pneumatic type, is mounted on the frame 12 so as to be rotatable on a third shaft 84 which is supported by bearing stands 86 horizontally and parallel to the primary shaft 10. The external end of a plunger 88 of the third actuator 82 is fixed to the first push board 78 on a surface thereof reverse to the one facingthe'second push board 80. A fourth actuator 90',

e.g. of the pneumatic type, is mounted on the frame 12 in a generally similar manner as the third actuator 82 but at a location and in the direction opposite to the latter with respectto the primary shaft 10. The external end of a plunger 92 of the fourth actuator 90 is fixed to the second push board on a surfacethereof re, verse to the one facing the firstlpush. board 78.

The distance between the two sets of grasping mech-- anisms Bean be varied dependingon the length of the wire glass sheet 70by sliding the bearing stands 14 and 18 and/or the first and-second rods; 20 and 22 along the first and second shafts l0 and 16 The thus constructed apparatus-ofv theinvention breaks off the side margin 70a of the w? :e glass .plate 70 by the following steps of operation.

Preliminary, a out line or knotch 94 is scored on the;

wire glass plate 70 by a separate device (notshown)- The apparatus of FIGS. l-3 is adjusted in such a man- I ner that the first rods 20, the second rods 22 and the fifth rods 34 are all parallel to the wire glass plate 70 and the plunger 56 of the second actuator 54 is substantially on the same horizontal plane as the glass plate 70. The glass plate 70 is preferably positioned such that the cut line 94 and thefirst and second shafts l0 and f 16 are substantially on a vertical plane. The plunger 56 is kept withdrawn in the actuator 54, so that the If, shaped support plates 64 are positioned to keep they.

glass-grasping plates 62 open or separate fromv each other as shown by the phantom lines in FIG. 3.

When the wire glass plate 70 is carried to a predetermined position, a detection means. such as a limit, switch or a photoelectric tube (not shown) causes the second actuator 54 to extend the plunger 56 thereof until the connecting rods 58 are brought into the vertical positions and the glass-grasping plates 62 are turned into the horizontal positions as seen in FIGS. 2 and 3., Thus the side margin70a of the glass plate 70 is held between the two grasping plates 62.

Then the third actuator 82 and the fourth actuator are actuated to extend the plunger 88 of the former and withdraw the plunger 92 of the latter. As a result, the first push board 78 is pushed together with the bracket,

74 and causes the primary shaft 10 to turn clockwise in FIG. 2 on its axis. The clockwise turn of the primary of FIG. 4 illustrate such movements of the rods. The diagram (I) represents the initial state and the diagram (II) does the state when the above operations of the third and fourth actuators 82 and 90 are completed. Such a movement of the fifth rods 34 causes naturally the glass-grasping plates 62 to exert a downward bend L ing force on the side margine 70a of the wire glass plate 70. As a result, the glass plate 70 is broken along the cut line 94, but the wires 96 may remain unbroken ei; ther partially or entirely as illustrated in the view (2) in' FIG. 5. A r

i In thenext step; the plunger 88 of the third actuator 82 is withdrawnitoturn the primary s'haftlO anticlockwise. Consequently, the third and'fourth rods 24 and 28 arepulled upvertically andthefifthrods 34,.make an anticlockwise rotational rrioveifient togethera with the glass-grasping plates 62,,The result of the movements of the rods in this step is shown-in the diagram.-(I-II)- ofare almost completely broken at thisstage.

Then the first'actuator 46 is actuated to withdraw the plunger 48 thereof. Accordingly,-the lower ends of the the phantom lines in FIG. 2 exert a pullingfor ce on the unbroken wires 96 as representedby, the arrow in the view (3.) of FIG. 5. {The wires 26 canbe completely bro: ken by this pulling force E, so that the side margin 70a is completely separated from the major. part ofthe wire; assp at 10.8 n n t e v e f IG A this stage the second actuator.54 draws back the plunger 56 so that :the glass-grasping plates 62 moveto enlarge the space therebetween. The separated side margin 7 04,

naturally falls,.e .g., intoa hopper (not shown) for the recovery thereof I x n w I After the release of the side margin 70a, the third actuator 82 is freed from the pneumatic pressureand the:

fourth actuator 90 is operated to rotate the bracket 76' anticlockwise FIG. 2. Due to the dead loads of the linked rods blocks A,. the primary shaftlfl turns on its axis clockwise in FIG. 2 until the first pusliboard 78' cornesjnto contact with the pushed-back second push board 80. If the capacity of the fourthactua'tor 90 is larger than that of the third actuator 82, the above turn of the primary shaft 10 may be caused by the movement of the plunger 88 to push the first push board 78. Thus the linked rods blocks A including the grasping mechanisms B return to their initial or standby positions, and one cycle of the operation is completed.

As seen from the above description, the essential features of this apparatus reside in the linkage method of the first to fifth rods 20, 22, 24, 28 and 34 and the rotational movement of the support plates 42 with respect to the fifth rods 34. The driving mechanism C and the glass-grasping mechanism B may be modified with equivalent functions either in construction or in elements by the use of various conventional elements and- /or systems. Each of the three pairs of the horizontal rods 20, 22 and 34 may be replaced with an appropriately shaped single rod or arm. The apparatus of FIGS. 1-3 may be rearranged by 90 rotation for the application to a vertically positioned wire glass plate.

The rod linkage characteristic of the invention will be summarized with reference to the view (I) of FIG. 4. The first rod 20, the second rod 22 and the fifth rod 34 are arranged parallel to and separate from each other. An end of the fifth rod 34 is connected with the glassgrasping plates 62 in such a manner that the glass plate 70 can be held parallel to the fifth rod 34 and the first.

shaft 10. The third rod 24 is pivotally and perpendicularly linked with the fifth rod 34 at a first distance from I the afore-mentioned end thereof. The fourth rod 28 is arranged parallel to the third rod 24 and pivotally linked with the first rod 34 at a second distance longer than the first distance from the end thereof. The first rod is pivotally linked with both the third and fourth rods 24 and 28 and fixed to the first shaft 10, which has a fixed .axistperpendicular-to both the fifth rod 34 and the third rod 24, a1 a third distanceifrom the third rod 24.1in the direction of-the glass-grasping plates 62. The

second -.rod 22 is pivotally-linked with either the third or fourth rods 24 and.28',u-with the former in this case,

. and fixed to the-secondsha'ftslfi, which hasa fixed axis parallel to the first shaft"=l0,- at the third distance from thethir'drod 24 in-'the= same dir'ection. The driving mechanism C'of FIGJT is"asso'ci'ated with one of the 1 first and s'corid shaftslU and-l6,with'the former in this casei'According' to such an-arrangement, there is p'rodiiceda'quadri-j oi'n't parallelogram by the fourrods 24,28,20and34. 1

A sfiesc'rib'edpreviouslyf thegl'ass-graspingplates 62 Due t'o such iarod linkage to the parallelogram, the fifth rod 34 and Hence the glass-grasping plates 62 can rotat efsir nultaneouslyand identically with the first rod 2t) around the cut line 9 4in either th e clockwise or anticlockwise direction. Three of the four sides this parallelogram necessarily formed by the fifth rod 34' and theltwo parallel and vgpigai rods 24 and'28. The remaining one side is, how ever, not necessarily formed by the first rod 20"as shown; the diagram (I flflqktgbutrnay be the second rod sincei the latter has substantially the .sarrie function as the former. Therefore; the above. describedhrod linkzigei may bie modified to any arrangement of FIGS. o ltlwith the sameactionofthe fifth rod and the glass-grasping plates-'62. V w l It will be. understood that the first and .second turns,

of the first shaft 10 maybe repeated a plurality of times prior to-the rotationofthe support plates 42 when gh e. wires 96 are too strong to break by the above described one cycle of operation. Apparatus of the invention is naturally applicable to a plain plate glass having no wire with omission of the second turn of the first shaft 10 and the rotation of the support plates 42.

What is claimed is: 1. Apparatus for breaking off a part of a wire glass plate along a cut line scored thereon, comprising:

first means to grasp the part of the wire glass plate in a predetermined position mounted on a support member;

a first rod arranged parallel to the wire glass plate in said position, an end thereof being pivotally joined with said support member such that said support member is rotatable in a plane perpendicular to the wire glass plate in said position;

a second rod pivotally and perpendicularly linked with said first rod at a first distance from said end;

a third rod arranged parallel to said second rod and pivotally linked with said first rod at a second distance longer than said first distance from said end;

a fourth rod pivotally linked with said second and third rods and arranged parallel to and separate from said first rod, said fourth rod being fixed to a first shaft having a fixed axis perpendicular to both said first and second rods at a third distance from said second rod in the direction of said first support member;

a fifth rod pivotally linked with at least one of said second and third rods and arranged parallel to and separate from said fourth rod, said fifth rod being fixed to a second shaft having a fixed axis parallel to said first shaft at said third distance from said second rod in-the same direction;

second means to turn one of said first and second shafts on said fixed axis thereof such that said one shaft is subjected to at least one cycle of turns consisting of a first turn through a first angle, a second turn in the reverse direction through a second angle larger than said first angle and a third turn into the initial position thereby to rotate said fourth, fifth and first rods and said first means all in the same direction through movements of said second and third rods along the respective axis thereof; and

third means to hold said support member normally in such a position that the part of the wire glass plate is kept parallel to said first rod and rotate said support member around an axle for joining said first rod therewith when said second turn of said one shaft is completed thereby to exert a pulling force I on the wires of the wire glass plate lying across the cut line.

2. Apparatus according to claim 1, wherein said first means comprises: an actuator having a plunger extendable towards and parallel to the wire glass plate in said position; a pair of connecting rods pivotally joined with the exterior end of said plunger to extend aslant and forwards therefrom in the symmetric directions with respect to said plunger; a pair of angled members, a side of each thereof being pivotally joined with the extended erid of said connecting rod and the other side thereof being pivotally joined with said support member; and a pair of grasping plates, a side of each thereof being fixed to said other side of said each angled member such that said grasping plates face normally aslant to the two'surfaces of the wire glass plate in said posi- 8 tion, respectively; said connecting rods and angled members being arranged such that said angled mem bers rotate in a plane perpendicular to the wire glass plate in said position until said grasping plates come into parallel Contact with the wire glass plate when said plunger is extended.

3. Apparatus according to claim 1, wherein said third means comprises an actuator having a plunger and pivotally mounted on a rigid member fixed to said first rod, said actuator being arranged such that the longitudinal axis of said plunger is parallel to said first rod and that the exterior end of said plunger is pivotally joined with said support member at a location substantially remotest from the linking point of said support member with said first rod.

4. Apparatus according to claim 1, wherein said fifth rod is spaced from said first rod in the same direction as and at a longer distance than said fourth rod and linked with said second rod.

5. Apparatus according to claim 1, wherein said fifth rod is spaced in the same direction as and at a longer distance than said fourth rod and is linked with said third rod.

6. Apparatus according to claim 1, wherein said fifth rod is spaced from said first rod in the same direction as and at a shorter distance than said fourth rod and linked with said second rod.

7. Apparatus according to claim 1, wherein said fifth rod is spaced from saidfirst rod in the opposite direction to said fourth rod and linked with said third rod.

8. Apparatus according to claim 1, wherein said fifth rod is spaced from said first rod in the opposite direction to said fourth rod and linked with said second rod. 

1. Apparatus for breaking off a part of a wire glass plate along a cut line scored thereon, comprising: first means to grasp the part of the wire glass plate in a predetermined position mounted on a support member; a first rod arranged parallel to the wire glass plate in said position, an end thereof being pivotally joined with said support member such that said support member is rotatable in a plane perpendicular to the wire glass plate in said position; a second rod pivotally and perpendicularly linked with said first rod at a first distance from said end; a third rod arranged parallel to said second rod and pivotally linked with said first rod at a second distance longer than said first distance from said end; a fourth rod pivotally linked with said second and third rods and arranged parallel to and separate from said first rod, said fourth rod being fixed to a first shaft having a fixed axis perpendicular to both said first and second rods at a third distance from said second rod in the direction of said first support member; a fifth rod pivotally linked with at least one of said second and third rods and arranged parallel to and separate from said fourth rod, said fifth rod being fixed to a second shaft having a fixed axis parallel to said first shaft at said third distance from said second rod in the same direction; second means to turn one of said first and second shafts on said fixed axis thereof such that said one shaft is subjected to at least one cycle of turns consisting of a first turn through a first angle, a second turn in the reverse direction through a second angle larger than said first angle and a third turn into the initial position thereby to rotate said fourth, fifth and first rods and said first means all in the same direction through movements of said second and third rods along the respective axis thereof; and third means to hold said support member normally in such a position that the part of the wire glass plate is kept parallel to said first rod and rotate said support member around an axle for joining said first rod therewith when said second turn of said one shaft is completed thereby to exert a pulling force on the wires of the wire glass plate lying across the cut line.
 2. Apparatus according to claim 1, wherein said first means comprises: an actuator having a plunger extendable towards and parallel to the wire glass plate in sAid position; a pair of connecting rods pivotally joined with the exterior end of said plunger to extend aslant and forwards therefrom in the symmetric directions with respect to said plunger; a pair of angled members, a side of each thereof being pivotally joined with the extended end of said connecting rod and the other side thereof being pivotally joined with said support member; and a pair of grasping plates, a side of each thereof being fixed to said other side of said each angled member such that said grasping plates face normally aslant to the two surfaces of the wire glass plate in said position, respectively; said connecting rods and angled members being arranged such that said angled members rotate in a plane perpendicular to the wire glass plate in said position until said grasping plates come into parallel contact with the wire glass plate when said plunger is extended.
 3. Apparatus according to claim 1, wherein said third means comprises an actuator having a plunger and pivotally mounted on a rigid member fixed to said first rod, said actuator being arranged such that the longitudinal axis of said plunger is parallel to said first rod and that the exterior end of said plunger is pivotally joined with said support member at a location substantially remotest from the linking point of said support member with said first rod.
 4. Apparatus according to claim 1, wherein said fifth rod is spaced from said first rod in the same direction as and at a longer distance than said fourth rod and linked with said second rod.
 5. Apparatus according to claim 1, wherein said fifth rod is spaced in the same direction as and at a longer distance than said fourth rod and is linked with said third rod.
 6. Apparatus according to claim 1, wherein said fifth rod is spaced from said first rod in the same direction as and at a shorter distance than said fourth rod and linked with said second rod.
 7. Apparatus according to claim 1, wherein said fifth rod is spaced from said first rod in the opposite direction to said fourth rod and linked with said third rod.
 8. Apparatus according to claim 1, wherein said fifth rod is spaced from said first rod in the opposite direction to said fourth rod and linked with said second rod. 